1. Field of the Invention
This invention relates to catheters for use within the body of a patient, and more particularly to aspiration and delivery catheters where the guidewire and aspiration or delivery lumens are not separate from each other.
2. Background of the Invention
Catheters have long been used for the treatment of diseases of the cardiovascular system, such as treatment or removal of stenosis. For example, in a percutaneous transluminal coronary angioplasty (PTCA) procedure, a catheter is used to insert a balloon into a patient's cardiovascular system, position the balloon at a desired treatment location, inflate the balloon, and remove the balloon from the patient. Another example is the placement of a prosthetic stent that is placed in the body on a permanent or semi-permanent basis to support weakened or diseased vascular walls to avoid catastrophic rupture thereof.
Often, more than one interventional catheter is used during a procedure, such as to change the size of the balloon being used or to introduce additional devices into the system to aid with the procedure, including delivery and aspiration catheters. In such situations, the catheters are generally inserted into the patient's cardiovascular system with the assistance of a guidewire. For example, a guidewire is introduced into the patient, steered through the tortuous pathways of the cardiovascular system, and positioned at a predetermined location. Various catheters having a guidewire lumen adapted to receive the guidewire may then be introduced into and removed from the patient along the guidewire, thereby decreasing the time needed to complete a procedure.
The treatment or removal of stenosis may introduce thrombi and/or emboli into the bloodstream. These particles can actually worsen a patient's condition by blocking the body lumen in the vicinity of the treatment area, or the particles can migrate to other parts of the body and create blockages in those areas. If the body lumen becomes occluded, the patient may suffer deleterious or even life-threatening effects, such as myocardial infarction or stroke.
Many techniques exist for preventing the release of thrombotic or embolic particles into the bloodstream during such a procedure. Common among these techniques is to introduce an occlusive device or a filter downstream of the treatment area to capture these embolic or thrombotic particles. The particles may then be removed from the vessel with the withdrawal of the occlusive or filtering device. In another common technique, the particles may be removed by an aspiration catheter prior to the withdrawal of these devices.
Two types of catheters commonly used in angioplasty procedures are referred to as over-the-wire (OTW) catheters and rapid exchange (RX) catheters. A third type of catheter with preferred features of both OTW and RX catheters, that is sold under the trademarks MULTI-EXCHANGE™, ZIPPER MX™, ZIPPER™, and/or MX™, is discussed below. An OTW catheter's guidewire lumen runs substantially the entire length of the catheter and is attached to, or enveloped within, the catheter shaft. Thus, the entire length of an OTW catheter is tracked over a guidewire during a PTCA procedure. A RX catheter, on the other hand, has a guidewire shaft that extends within only the distalmost portion of the catheter. Thus, during a PTCA procedure only the distalmost portion of a rapid exchange catheter is tracked over a guidewire. In both instances, the guidewire lumen and the main lumen of the catheter are separate from each other.
An aspiration catheter may be designed such that a guidewire is contained within the aspiration lumen as the catheter is advanced thereover, or the aspiration catheter may include a guidewire shaft extending along substantially the entire length of the aspiration catheter such that the guidewire is disposed therein as the catheter is advanced through a body lumen.
While over-the-wire catheters are advantageous in many ways, deploying and exchanging the aspiration catheter can be difficult. In order to maintain a guidewire in position while withdrawing an indwelling aspiration catheter, the clinician must grip the proximal end of the guidewire to prevent it from becoming dislodged during removal of the aspiration catheter. However, the aspiration catheter, which is typically on the order of 135 centimeters long, is generally longer than the exposed portion of the guidewire. Therefore, to be able to maintain the guidewire in place, the guidewire must be sufficiently long so that the clinician may be able to maintain a grip on an exposed portion of the guidewire. For aspiration catheters on the order of 135 centimeters in length, therefore, a guidewire of 300 centimeters in length is necessary. Manipulating an aspiration catheter along such a long guidewire typically requires more than one operator, thereby increasing the complexity of the process, and potentially compromising the sterility of the procedure.
A guidewire of a shorter length may be used during the procedure, but during the exchange process, such as when an indwelling therapeutic catheter is exchanged for an aspiration catheter or when an indwelling aspiration catheter is exchanged for a therapeutic catheter, a longer exchange guidewire is substituted for the original guidewire. Also, as is disclosed in U.S. Pat. No. 4,917,103 to Gambale et al., incorporated herein by reference in its entirety, the length of the original guidewire may be extended using a guidewire extension apparatus.
Aspiration catheters may also be of the single operator or “rapid-exchange” (RX) type. An RX aspiration catheter typically includes a tubular catheter shaft with an aspiration lumen extending the entire length thereof and a guidewire shaft having a guidewire lumen of minimal length positioned along a distal portion of the catheter, although some of these catheters are not advanced over guidewires at all. As such, the guidewire is located outside of the aspiration catheter except for a short segment which extends within the guidewire lumen. Therefore, a clinician is able to control both ends of the guidewire while the aspiration catheter is loaded onto the guidewire. The aspiration catheter is then advanced through the patient with only a distal portion of the catheter riding on the guidewire.
While convenient for rapid and simple exchange, RX type catheters typically lack the desired stiffness and pushability for readily advancing the catheter through the tortuous vascular system. Furthermore, use of these catheters increases the likelihood of guidewire entanglement and may lead to damage of the vascular walls due to the tension load applied to the guidewire. Although a single clinician may be able to deploy such an aspiration catheter, the long proximal end of the catheter is still relatively difficult to manipulate, thereby increasing the complexity and duration of the deployment of the aspiration catheter.
Another catheter designed for fast and simple catheter exchange is sold by Medtronic Vascular, Inc. of Santa Rosa, Calif. under the trademarks MULTI-EXCHANGE™, ZIPPER MX™, ZIPPER and/or MX™ (hereinafter referred to as the “MX™ catheter”). An MX catheter is disclosed in U.S. Pat. No. 4,988,356 to Crittenden et al., and in co-pending U.S. patent application Ser. No. 10/116,234, filed Apr. 4, 2002, both of which are incorporated herein by reference in their entireties.
The MX™ catheter includes a catheter shaft having a guideway that extends longitudinally along the catheter shaft and that extends radially from a guidewire lumen to an outer surface of the catheter shaft. A guide member through which the shaft is slidably coupled cooperates with the guideway such that a guidewire may extend transversely into or out of the guidewire lumen at any location along the guideway's length. By moving the shaft with respect to the guide member, the effective over-the-wire length of the MX™ catheter is adjustable.
Additionally, U.S. patent application Ser. No. 10/712,374, filed Nov. 14, 2003, incorporated herein by reference in its entirety, discloses a catheter with a full-length guidewire shaft with a proximal portion comprised of a plurality of independent segments, or clips that hold a guidewire in place along a proximal portion of the catheter and allow access to the guidewire along the proximal portion of the catheter from between adjacent clips.
It is among the general objects of the present invention to provide an alternative catheter design which also allows for fast and simple catheter exchange. What is needed is a catheter which allows for single operator catheter exchange without the use of a guidewire extension. Accordingly, the present invention provides a catheter that includes a single lumen that is configured to receive a guidewire and to perform the function of the catheter.